July 27, 2010

Neolithic and modern Chinese craniofacial variation (Wu et al. 2010)

The PCA loadings on the cranial variables used are shown in Table 2. As usual for craniometric analyses, PC1 is an overall "size" factor, with positive loadings on all variables.

PC2 which distinguishes north from south is associated with high face (nasion-prosthion height), narrow nose (nasal breadth), and high eye sockets (orbital height). Notice that the sign is reversed for Modern-day vs. Neolithic Chinese, but the combination of traits is preserved (e.g. low eye sockets with broad noses).

PC3 is associated with broad and short skulls and eye sockets, and low noses.

Table 3 in the paper shows the differences between the Neolithic-era and modern Chinese, with the six significant changes being: lower skull, narrower face, narrower nose, higher orbits, lower face, narrower orbits in the modern sample.

The results of the craniometric analysis are quite similar to those arrived by genetics, which show that north-south being the main axis of differentiation within East Asia.

It is also quite interesting that this distinction also finds parallels in Y-chromosome distribution, with "northern C3" and "southern O3", while an earlier study found greater differentiation between northern and southern Chinese based on mtDNA rather than Y-chromosomes.

The north-south genetic structure of the Han Chinese was made most evident in this recent paper.

You can also take a look at some (non-Han) ethnic groups of China, where differences between northern/southern populations, similar to those discovered in this paper are quite evident.

International Journal of Osteoarchaeology doi:10.1002/oa.1190

Craniofacial variation between southern and northern Neolithic and Modern Chinese

X. J. Wu et al.

Abstract

Previous studies propose that the Yangtze River is the geographic boundary separating northern and southern Chinese populations. In order to test this hypothesis, 19 Neolithic and 15 Modern human cranial samples from north of the Qinling Mountain Range, south of the Yangtze River and in between were chosen for morphometric analysis. Our results indicate that cranial variation exists in Holocene Neolithic and Modern northern and southern Chinese. In the Neolithic sample, the northern Chinese crania are characterised by greater upper face height and orbit height, while the southern Chinese skulls are depicted by a wider nose. The morphology of the crania between the Qinling Mountain range and the Yangtze River feature a mosaic of characters that suggest affiliation with both north and south groups. In the Modern day sample, northern crania are characterised by a broad and wide face, and a tall nose. From the Neolithic to Modern day, a series of microevolutionary processes that apply to both the northern and southern samples can be discerned. Overall, the head gets lower, the face and nose become narrower and the orbits tend to be narrower and higher. Our results support the suggestion that the Qinling Mountain Range and the Yangtze River represent a natural barrier to the movement of Chinese populations. Climatic variation and the transition to an agricultural lifestyle are proposed as the primary factors influencing human craniofacial morphologies.

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